PROJECT SUMMARY Bacterial vaginosis (BV) is a dysbiosis of the vaginal microbiome characterized by low levels of lactobacilli, which typically dominate the vagina in healthy women, and overgrowth of diverse anaerobic bacteria, most notably, Gardnerella vaginalis (G.v.). BV affects ~30% of U.S. women and is associated with increased risk of adverse pregnancy outcomes, postsurgical infections, and sexually transmitted infections (STIs). Current treatment options, primarily comprised of orally- or topically-applied antibiotics, are initially efficacious; however, frequent relapse is prevalent, contributing to recurrent BV infections and adverse side effects. Potential new therapies, including prebiotics, metabolic products (e.g., lactic acid), and probiotics (lactobacilli) are being studied for their abilities to re-balance the vaginal microbiome toward ?normal? Lactobacilli and counterbalance G.v. However, these and other methods of BV treatment often require repeated vaginal administrations, which can limit their convenience and appropriate use. New delivery vehicles that can store and release lactic acid and probiotic lactobacilli are needed. However, significant gaps remain in our understanding of host, microbe, and delivery vehicle interactions, contributing to the difficulty in attaining a long-term, effective method of protection and treatment against BV. In this project, we seek to develop new therapies to alter BV pathogenesis, while advancing the understanding of delivery vehicle interactions with the host and vaginal microbes. To achieve these goals, we will optimize the design of a novel delivery platform composed of sequentially-layered or dual-spun polymeric electrospun fibers (EFs) that deliver probiotics, test their efficacy in vitro, and assess the safety and effectiveness of these fibers in a murine model of BV. These studies will provide the foundation for improved therapeutic outcomes, while providing new insight into the effects of lactic acid-based, probiotic fibers on vaginal microbes, host inflammatory response, and BV disease markers and progression. While we will initially apply this delivery approach to target BV pathogenesis, we envision the research outcomes will have a significant impact on the development of future multipurpose platforms to prevent and treat broader, more complex interactions between bacterial and viral pathogens in the female reproductive tract.